1. Field of the Invention
This invention relates to telephone answering devices, and more particularly to a module for disconnecting an established telephone connection between a telephone line and a telephone answering device in response to user-transmitted DTMF tone codes.
2. Description of the Related Art including information disclosed under 37 C.F.R. .sctn.1.97-1.99
Recent developments in telephone answering devices now allow several telephone answering devices (TADs) to share the same telephone line. Each TAD operates independently of all the others. In order to coordinate the activities of all the TADs, only one TAD answers the incoming telephone call while the others remain passive until activated by a code entered by the caller. The answering TAD is designated as the main or master TAD (MTAD). The passive TADs are designated as extension TADs or ETADs.
When the MTAD answers the incoming telephone call, the caller is informed by an outgoing voice message that entry of a tone code from the dual-tone multi-frequency (DTMF) keypad present at the caller's telephone will activate one of the passive ETADs. As each ETAD has its own unique tone code, the caller can activate one of possibly several ETADs sharing the same telephone line.
While the caller can uniquely activate one of several ETADs in order to preserve the privacy of any telephone message that might be left by the caller, the MTAD must be disconnected or otherwise rendered inactive so that it does not also record the caller's message. Previously, the MTAD was disconnected from the telephone call by a disconnect module that temporarily broke the connection between the MTAD and the telephone line. Such a disconnect module was powered in the usual manner, namely by a connection to a wall socket or by a battery. However, requiring outside power for the disconnect module could prevent the use of an MTAD/ETAD system, or make such use inconvenient. If batteries were used, periodic replacement of the batteries is required.